1. Field of the Invention
The invention relates to ceramic igniters and improved methods for making the igniters.
2. Background
Ceramic materials have enjoyed great success as igniters in gas fired furnaces, stoves, clothes dryers, and other devices that require ignition of gaseous fuel. Ceramic igniter production requires constructing an electrical circuit through a ceramic component, a portion of which is highly resistive and rises in temperature when electrified by a wire lead.
One conventional igniter, the Mini-Igniter.TM., available from the Norton Igniter Products of Milford, N.H., is designed for 12 volt through 120 volt applications and has a composition comprising aluminum nitride ("AlN"), molybdenum disilicide ("MoSi.sub.2 "), and silicon carbide ("SiC").
U.S. Pat. No. 5,786,565 to Willkens et al. (the "565 patent") discloses highly useful ceramic igniters that comprise a) a pair of electrically conductive portions, each portion having a first end, b) a resistive hot zone disposed between and in electrical connection with each of the first ends of the electrically conductive portions, the hot zone having an electrical path length of less than 0.5 cm, and c) an electrically non-conductive heat sink material contacting the hot zone.
A variety of performance properties are required of ceramic igniter systems, including high speed (low time to heat from room temperature to design temperature) and sufficient robustness to operate for extended periods without replacement. Many conventional igniters, however, do not consistently meet such requirements. It thus would be desirable to have new ceramic igniter systems.